Conventionally, there is generally adopted parallel communication, in communication between integrated circuits such as LSIs (Large Scale Integrations) and between modules, in which bits of data with N-bit width are transmitted from a transmission side to a reception side via N-signal lines provided in parallel with each other.
In the parallel communication, degeneration control of transmission channels is often performed in such a manner that the N-signal lines are divided into several segments and all the signal lines included in a segment that contains even a single signal line on which a communication error occurs caused by noise or jitter are made unusable. With the degeneration control, the possibility of occurrence of a subsequent communication failure can be avoided, which allows reliability of communication to be enhanced.
For example, a transmission-side interface divides transmission data into words (1 word=32 bits), adds ECC (Error Check Code) data to each word, uses transmission channels corresponding to the words, and transmits the data to a reception-side interface. In this case, there is known a conventional technology for performing the degeneration control in which when transmission anomaly is detected by performing check on the data using the ECC data in the reception-side interface, a corresponding transmission channel is made unusable.
For the data transmitting/receiving devices, in communication between LSIs or modules, a transmission-side data transmitting device divides transmission data into divided data, generates ECC data for the respective divided data, serially transmits the divided data to the reception side, and, thereafter, collectively transmits the ECC data to a reception-side data transmitting device. As for the reception-side data transmitting device, there is known a conventional technology in which it performs check on corresponding divided data previously received and performs error correction on the received divided data based on the received respective ECC data.
A data transfer system, in communication between LSIs, is configured that an LSI as a data transfer source transfers transmission data to an LSI as a data transfer destination. The LSI as the data transfer destination, if there is an error in received data, requires retransmission of the data of the LSI as the data transfer source. As for the LSI as the data transfer source, there is known a conventional technology in which it performs verification/correction on the transmission data and then transmits the transmission data to the LSI as the data transfer destination.
However, of the conventional technologies, the data transmission system performing the degeneration control for making unusable a transmission channel where transmission anomaly is detected has a problem of inefficient use of the signal lines such that when the transmission anomaly is detected in a transmission channel on a word basis, even if only a signal line of one bit is actually anomalous, all the signal lines for one word are made unusable, which causes large reduction of a transmission rate of the data from the transmission-side interface to the reception-side interface, and any actually usable signal line of the signal lines made unusable is made inactive.
Moreover, originally, of the conventional technologies, the technology for not disconnecting a signal line on which transmission anomaly occurs has a problem in which even if a physical failure occurs on the signal line, error correction of ECC and retransmission of transmission data should be performed as long as the signal line is continuously used, which causes necessity of wasteful processes.    Patent document 1: Japanese Laid-open Patent Publication No. 2006-186527    Patent document 2: Japanese Laid-open Patent Publication No. 2005-354310    Patent document 3: Japanese Laid-open Patent Publication No. 2003-345677